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WO1997036663A1 - Procede de separation en deux etapes - Google Patents

Procede de separation en deux etapes Download PDF

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Publication number
WO1997036663A1
WO1997036663A1 PCT/US1997/005233 US9705233W WO9736663A1 WO 1997036663 A1 WO1997036663 A1 WO 1997036663A1 US 9705233 W US9705233 W US 9705233W WO 9736663 A1 WO9736663 A1 WO 9736663A1
Authority
WO
WIPO (PCT)
Prior art keywords
liquid phase
separator vessel
phase
process according
gases
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1997/005233
Other languages
English (en)
Inventor
Richard W. Lehmann
Russell G. Forbess
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Water Applications and Systems Corp
Original Assignee
United States Filter Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by United States Filter Corp filed Critical United States Filter Corp
Priority to CA002250888A priority Critical patent/CA2250888C/fr
Priority to AU25987/97A priority patent/AU2598797A/en
Publication of WO1997036663A1 publication Critical patent/WO1997036663A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D19/00—Degasification of liquids
    • B01D19/0063—Regulation, control including valves and floats

Definitions

  • This invention is concerned with a multiple stage separation process for gaseous and liquid phases from a wet oxidation system.
  • Wet oxidation is a well known process for treatment of aqueous wastewaters.
  • the process involves heating a mixture of the wastewater plus an oxygen-containing gas to elevated temperature and pressure to effect oxidation of oxidizable substances contained in the wastewater.
  • All wet oxidation systems include one or more pressure control valves to regulate the flow of liquid, solids and gases from the high pressure part of the system to the low pressure part of the system.
  • Meidl et al. in U.S. Patent No. 4,620,563 disclose a blowdown pot with an inlet pressure control valve through which the pot receives unwanted residue e.g., ash from a high pressure chemical reactor.
  • This reactor residue can be continuously or semi-continuously blown out from the high pressure, high temperature chemical reactor into the relatively low pressure blowdown pot which includes means for maintaining al liquid level therein, thus minimizing steam flashing vessel wear.
  • Depuydt et al. disclose a pressure control valve with a valve seat and support assembly which extends beyond the valve body to prevent erosion by the blowdown slurry.
  • the apparatus also includes a displacement-compensating seal between the valve and receiving vessel to allow for thermal expansion and contraction during the blowdown cycle while maintaining the integrity of the seal.
  • Lehmann et al. in U.S. Patent No. 5,389,264 disclose a process for dissipating the energy of a wet oxidation mixture after that stream traverses a pressure control valve.
  • the depressurized stream is discharged into a phase separator vessel containing a gas phase and a liquid phase.
  • the pressure control valve is positioned to discharge the oxidation mixture at a selected orientation below the surface level of the liquid phase in the vessel. This dissipates the energy of the mixture and prevents erosion of the phase separator vessel.
  • a single stage separator vessel operating essentially at atmospheric pressure is employed in a wet oxidation flow scheme to effect separation of liquid and gaseous phases once the oxidized effluent mixture traverses the pressure control valve which maintains system operating pressure.
  • This single stage separation produces a liquid effluent which may not be suitable for all applications.
  • significant amounts of gases such as C0 2 , N 2 , and O 2 , can remain dissolved in the separated liquid phase.
  • gases such as C0 2 , N 2 , and O 2
  • this liquid effluent is stored in a covered collection tank, these dissolved gases can come out of solution and collect within that tank, causing operational problems.
  • the separated gas phase may require further treatment which entails movement of the whole volume of gas through that treatment process. Transfer of the gas requires expenditure of energy in some form, such as a blower, a compressor, or the like, entailing additional operating expense.
  • the gas phase from a single stage separator at atmospheric pressure contains a significant amount of water vapor. The water vapor adds expense to downstream gas phase treatment such as passage through a high temperature afterburner. Condensation of this water vapor can result in corrosion to the equipment in contact with the gas phase as well.
  • the gas/liquid mixture from a wet oxidation process operating at elevated temperature and pressure is cooled by flowing through a process heat exchanger or other cooling means.
  • the cooled oxidation mixture then traverses a pressure control valve to reduce the pressure to that sufficient to move the gas phase to any downstream treatment.
  • the partially depressurized mixture flows into a first phase separation vessel where noncondensible gases are separated from liquid which is still saturated with gases at this operating pressure.
  • the first separator has an upper gas outlet conduit controlled by a pressure controller and a pressure control valve and a lower liquid outlet conduit controlled by a level controller and a level control valve.
  • the liquid phases, saturated with gases, is depressurized through the liquid level control valve and flows to a second phase separation vessel operated essentially at atmospheric pressure.
  • the depressurization removes the dissolved gases from the liquid phase in the second separator vessel.
  • the gas phase from the second separator may be routed to further treatment or discharged to the environment.
  • the liquid phase, now containing little if any dissolved gases may be stored in a suitable vessel or discharged to further treatment if necessary.
  • This staged separator sequence fully degasses the liquid and prevents gases from collecting in an effluent storage vessel where the presence of a gas phase is undesirable.
  • the pressurized gases from the first separator vessel still contain some energy, and need only to be routed to further treatment in this relatively low pressure state.
  • a pH adjusting substance is added to the liquid effluent to provide a liquid phase pH suitable for further treatment or discharge of the liquid effluent.
  • FIGURE 1 shows a schematic diagram for the two stage separation process applicable to the effluent from a wet oxidation system.
  • wet oxidation systems operate at 150° - 350°C and at pressures of at least 100 psig, up to about 3,500 psig.
  • an oxidized cooled wet oxidation mixture in a conduit 10 flows through a pressure control valve 12 which depressurizes the oxidation mixture to a pressure sufficient to move the gas phase to any downstream treatment, including passage through all necessary control valves.
  • a pressure of about 10 psig is sufficient for this purpose, although higher pressures may be suitable or even required in some situations.
  • the partially depressurized mixture flows through another conduit 14 and into a first separator vessel 16 where the gaseous phase and the liquid phase separate.
  • the pressure within the first separator vessel is maintained at the desired superatmospheric pressure (at least about 10 psig) by a pressure controller 18 which operates a pressure control valve 20.
  • This valve 20 controls the gaseous phase flow through the outlet conduit 22 exiting near the top of the separator vessel 16.
  • a demister device 24 may assist in phase separation within the vessel.
  • a gas/liquid scrubber 21 may be located between the first separator vessel 16 and the pressure control valve 20 to condition the gas stream flowing through the outlet conduit 22 prior to the gas phase traversing the pressure control valve 20.
  • the liquid phase is maintained at the desired level in the vessel 16 by a level controller 26 which operates a level control valve 28.
  • This valve 28 controls the liquid phase flow through the outlet conduit 30 exiting near the bottom of the first separator vessel 16.
  • the majority of the noncondensible material in the oxidized effluent mixture enters the gaseous phase in the first separator vessel 16.
  • the liquid phase is saturated with gases at the operating pressure of this first stage of separation which ranges upward from about 10 psig.
  • the great majority of the gases are separated into the gaseous phase.
  • the pressure controller 18 maintains the desired pressure (at least about 10 psig) by modulating the flow of the gaseous phase through the conduit 22 using the pressure control valve 20.
  • the level controller 26 As the liquid level rises, which is sensed by the level controller 26, a portion of the liquid flows through the exit conduit 30, through the level control valve 28, and through a conduit 32 to a second separator vessel 34 operated essentially at atmospheric pressure. Thus, the operating pressure and liquid level within the first separator vessel are maintained within selected operating parameters.
  • the gas saturated liquid phase encounters essentially atmospheric pressure conditions and the soluble gases are transferred to the gaseous phase which exits the vessel 34 via a vent conduit 36.
  • a demister 38 may be used to retain fine droplets of liquid in the vessel 34.
  • the liquid phase in the second separator is maintained at the desired level in that vessel 34 by a second level controller 40 which operates a second level control valve 42.
  • This valve 42 controls the liquid phase outlet flow through the conduit 44 exiting near the bottom of the second separator vessel 34.
  • a centrifugal pump 43 connected in the liquid phase outlet conduit 44, ahead of the level control valve 42, may assist in removing the liquid from the second separator vessel 34.
  • the majority of the gaseous components from the wet oxidation mixture are separated into a first gas phase in the first separator vessel 16.
  • This pressurized gas can be routed to further treatment without imparting additional energy to the gas.
  • the pressurized gases from the first separator vessel have a reduced water vapor content compared to the gases discharged from a system without a pressurized separator.
  • the reduced water vapor content decreases the cost of downstream gas phase treatment, such as passage through a high temperature afterburner.
  • corrosion of the gas phase handling equipment in contact with water condensed from the gases is minimized by low humidity gases. This pressurized separation thus improves the handling and further treatment of these pressurized gases.
  • the volume of gas phase generated in the second separator vessel 34 is generally quite small. Only the gases soluble in the liquid phase entering from the first separator vessel are liberated within the second separator vessel. The liquid phase exiting from the second separator vessel 34 via the exit conduit 44 is essentially free of excess dissolved gases. There is no supersaturation of the separated liquid phase with gases as can occur with a single stage separator system. Thus any problems associated with dissolved gases coming out of solution from the oxidized liquid phase in downstream treatment or storage are avoided.
  • a pH adjusting substance either acidic or basic, is added to the liquid phase after it has passed from the first separator vessel 16 through the level control valve 28.
  • the pH adjusting substance stored in a tank 50, is added to the liquid in the conduit 32 from a conduit 52 supplied from a pump 54 drawing from the tank 50.
  • the amount of pH adjusting substance added is controlled by a pH controller 56 which monitors pH downstream of the addition point, such as within the second separator vessel 34.
  • the oxidized liquid phase from the first separator vessel 16 may have a basic pH and further biological treatment requires a pH near neutral.
  • the pH controller 56 adjusts the addition of acidic material to maintain the liquid pH within the second separator vessel in the pH range of 6 to 8.
  • an acid solution such as sulfuric or hydrochloric acid
  • This particular pH adjustment may result in the generation of additional gases, such as C0 2 , in the second separator vessel.
  • an acidic liquid effluent may require the addition of a solution of basic substance, such as caustic soda or metal carbonate, to neutralize the liquid to a pH suitable for discharge.
  • a solution of basic substance such as caustic soda or metal carbonate
  • this pH adjustment may result in the generation of additional gases in the second separator vessel.
  • the pH adjusting substance may be added to the oxidation mixture after it traverses the first pressure control valve 12, as it flows through the inlet conduit 14 to the first separator vessel 16.
  • the pH adjusting substance is added from a conduit 58, also supplied from the pump 54 drawing from the tank 50 to produce an oxidized liquid in the first separator vessel with pH in the preselected range.
  • any gases produced by the pH adjustment enter the gas phase found in the first separator vessel 16. In some cases it may be required to produce an oxidized liquid phase which is extremely acidic or basic. The pH adjusting steps described will accommodate such a requirement with little difficulty.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Treating Waste Gases (AREA)

Abstract

L'invention concerne un procédé visant à produire une phase liquide oxydée avec un minimum de gaz dissous provenant d'un système de traitement par oxydation en milieu liquide. Le mélange d'oxydation provenant du système de traitement pénètre dans une première cuve de séparation fonctionnant à une pression superatmosphérique où les phases liquide et gazeuse se séparent. Les gaz atmosphériques sont acheminés vers un autre traitement ou évacués dans l'environnement. La phase aqueuse s'écoule vers une seconde cuve de séparation fonctionnant à une pression essentiellement atmosphérique où les gaz dissous additionnels se séparent de la phase liquide. Les gaz sont évacués et la phase liquide est appropriée pour être stockée ou subir un autre traitement. L'invention concerne également l'ajustement du pH de la phase liquide au cours du procédé de séparation.
PCT/US1997/005233 1996-04-01 1997-03-31 Procede de separation en deux etapes Ceased WO1997036663A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CA002250888A CA2250888C (fr) 1996-04-01 1997-03-31 Procede de separation en deux etapes
AU25987/97A AU2598797A (en) 1996-04-01 1997-03-31 Two-stage separation process

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US61771196A 1996-04-01 1996-04-01
US08/617,711 1996-04-01

Publications (1)

Publication Number Publication Date
WO1997036663A1 true WO1997036663A1 (fr) 1997-10-09

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/005233 Ceased WO1997036663A1 (fr) 1996-04-01 1997-03-31 Procede de separation en deux etapes

Country Status (3)

Country Link
AU (1) AU2598797A (fr)
CA (1) CA2250888C (fr)
WO (1) WO1997036663A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004000423A1 (fr) * 2002-06-24 2003-12-31 Victoria Link Limited Ameliorations apportees ou associees a l'oxydation en milieu humide
CN105967490A (zh) * 2016-06-27 2016-09-28 东方电气集团东方锅炉股份有限公司 一种湿质有机废弃物的处理方法及连续式处理系统

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3630002A (en) * 1970-03-24 1971-12-28 Combustion Eng Separator control system
JPS5522367A (en) * 1978-08-07 1980-02-18 Asahi Chem Ind Co Ltd Treatment of high concentration waste water
EP0538848A1 (fr) * 1991-10-23 1993-04-28 Urea Casale S.A. Procédé et appareillage pour l'hydrolyse de l'urée résiduelle dans l'eau provenant des installations de synthèse d'urée
WO1994011310A1 (fr) * 1992-11-06 1994-05-26 Modar, Inc. Procede d'oxydation de matieres dans l'eau a des temperatures surcritiques a l'aide d'accelerateurs de vitesse de reaction
US5389264A (en) * 1993-07-12 1995-02-14 Zimpro Environmental Inc. Hydraulic energy dissipator for wet oxidation process
EP0686427A1 (fr) * 1993-12-28 1995-12-13 Nippon Shokubai Co., Ltd. Catalyseur pour le traitement des eaux usees, son procede de production, et procede de traitement des eaux usees au moyen d'un tel catalyseur
US5544672A (en) * 1993-10-20 1996-08-13 Atlantic Richfield Company Slug flow mitigation control system and method

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3630002A (en) * 1970-03-24 1971-12-28 Combustion Eng Separator control system
JPS5522367A (en) * 1978-08-07 1980-02-18 Asahi Chem Ind Co Ltd Treatment of high concentration waste water
EP0538848A1 (fr) * 1991-10-23 1993-04-28 Urea Casale S.A. Procédé et appareillage pour l'hydrolyse de l'urée résiduelle dans l'eau provenant des installations de synthèse d'urée
WO1994011310A1 (fr) * 1992-11-06 1994-05-26 Modar, Inc. Procede d'oxydation de matieres dans l'eau a des temperatures surcritiques a l'aide d'accelerateurs de vitesse de reaction
US5389264A (en) * 1993-07-12 1995-02-14 Zimpro Environmental Inc. Hydraulic energy dissipator for wet oxidation process
US5544672A (en) * 1993-10-20 1996-08-13 Atlantic Richfield Company Slug flow mitigation control system and method
EP0686427A1 (fr) * 1993-12-28 1995-12-13 Nippon Shokubai Co., Ltd. Catalyseur pour le traitement des eaux usees, son procede de production, et procede de traitement des eaux usees au moyen d'un tel catalyseur

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 004, no. 050 (C - 007) 16 April 1980 (1980-04-16) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004000423A1 (fr) * 2002-06-24 2003-12-31 Victoria Link Limited Ameliorations apportees ou associees a l'oxydation en milieu humide
US7332095B2 (en) 2002-06-24 2008-02-19 Victoria Link Limited Wet oxidation
CN105967490A (zh) * 2016-06-27 2016-09-28 东方电气集团东方锅炉股份有限公司 一种湿质有机废弃物的处理方法及连续式处理系统

Also Published As

Publication number Publication date
AU2598797A (en) 1997-10-22
CA2250888A1 (fr) 1997-10-09
CA2250888C (fr) 2006-08-01

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